FEATURES:
- Ability to add/edit keycode categories manually in the admin area.
- Ability to add/edit gift card codes manually in the admin area.
- Ability to send email for ordered keycode after purchasing.
- Ability to set maximum number of code that users can get.
- Ability to set maximum number...

1) You only need Credits (Lite) if you plan on giving away free codes?
2) You can enter a big list of codes at once, 1 code to a line, and that codes can only be given once and its on record who got what code?

Let us answer your questions
1. You can use Credits Lite with full features like Credits Premium for KeyCode => You can share / sell key code to your users.
2. You can enter a big list of code at once, 1 code per line and that code will be assigned for once people who got.

@******* Ok i got the add-on and just installed a long with Credits Lite, but i have a problem.
When i go to credits and Import Actions, and Import the "*******-credits-events.xml" It says it's done, but then when i go to make keycode category it says "This action is not active yet", but when i look in credits action list, there is no actions for keycode.